1. Field of the Invention
The present invention relates to the field of pipeline construction, and more particularly but not by way of limitation, to an improved apparatus for the transport, and coupling of pipe segments during the pipeline construction process.
2. Discussion of the Prior Art
The ability to transport fluids across long distances has been foundational to man's societal advancement for centuries. Pipelines today provide a very basic element to the infrastructure in our densely populated cities, whereby fresh water and heating fluids are delivered to, and waste materials are efficiently taken from, our homes. Millions of acres of arid farmland have been transformed into amber fields of grain due to the development of irrigation systems delivering water by pipelines. Pipeline transport of fluids is often a better solution than over the road trucking, such as the TransAlaska pipeline which traverses hundreds of miles of rugged and often impassible terrain.
Today, pipelines are assembled from individual pipe segments that are typically fabricated of steel or plastic in variable lengths, and have diameters of less than an inch to several feet. The individual segments are commonly heavy and difficult to manipulate into the proper position for constructing the joints between them.
Further complications arise when the pipeline is to be buried. In the case of an underground pipeline, the segments must either be joined in the trench, or joined above ground and lowered down into the trench following joint construction. Manual transportation and manipulation of the segments are labor intensive undertakings.
Man's dependence on pipelines has inspired the development of numerous pipeline construction devices. Devices invented early in this century aided in the support and manipulation of a pipeline, allowing inspection, insulation, painting, or repair. An example of this type of device is taught by U.S. Pat. No. 1,866,381 issued to Ward. The typical pipeline at that time was of welded joint construction for steel pipe, or mechanical joint construction for cast iron pipe.
About the middle of this century came the development of the spigot and friction gasket type joint, which continues today to be a leading type of pipeline joint construction. This type of joint offers an easier coupling method, dramatically reducing the time necessary to assemble it. The resulting joint is also significantly more reliable, in that it produces a more flexible yet fluid tight seal. The resulting pipeline performs with increased resistance to normally occurring and damaging effects such as pressure or temperature shock, vibration, earth movement, and expansion or contraction.
The friction gasket type joint was first developed as a collar into which two pipe segment ends were seated. Several devices were invented to aid in the assembly of this type of joint. Typically the devices provided for above ground construction of the joints. Two pipe segments being coupled were gripped and forced axially into the friction gasket joint. The pipeline was then transported into the trench to be buried. An example of this type of device is taught by U.S. Pat. No. 2,538,365 issued to Jones.
An improvement to the spigot and friction gasket construction followed closely with the development of pipe segments formed with an integral "belled pipe". The smooth end of a first pipe segment is inserted into the bell end of a second segment. The advantage of this belled pipe is further reduced joint complexity, primarily because only one pipe end rather than two has to be seated into the bell, and also because fewer parts are necessary. Numerous devices have been invented to aid in the construction of this type of pipeline joint. Typically these devices provide for gripping the segment being added to the pipeline, and for applying the necessary axial force to drive the smooth end of the first pipe segment into the bell end of the second, or already laid pipe segment. Examples of this type of device are taught by U.S. Pat. No. 3,036,372 issued to Vigneron, and U.S. Pat. No. 3,561,615 issued to Forsberg.
While these and other inventions have improved the speed and quality of joint construction, the overall process of pipeline construction remains a cumbersome and often dangerous task. The pipe segments are typically shipped to the jobsite mounted on a skid, with the bell end alternating from one end to the other on adjacent pipes. This provides a more dense packing of the skid. Individual pipe segments must be transported from the skid to the joint construction location, which moves each time a segment is added to the pipeline. The construction rate is slowed when the pipe segments must be handled in a constrained environment, such as a wooded area, or an uneven or unstable terrain.
Regulations of the Occupational Safety and Health Administration (OSHA) which apply to the pipe laying industry require that the walls of a trench 4 feet deep or more be shored if anyone is required to enter the trench during the pipeline construction process. It is therefore advantageous to keep all workers out of the trench by constructing the joints above ground and then placing the pipeline into the trench.
An improvement in the art would be a device that is capable of storing an inventory of pipe segments, transporting them along the pipeline providing a continuous supply at the moving joint construction location, and drawing from the inventory as pipe segments are added to the pipeline. Further improvement would be realized by a device that would aid in the manipulation of the pipe segments from the storage area to the joint construction location, thus minimizing the physical handling of the segments by the operator. Such a self-contained device could make it possible for a single operator to construct pipelines at a faster rate than that done by an entire crew of operators manually.